1. Field of the Invention
The present invention relates to a composition for the treatment of surfaces of copper or copper alloys which is useful in removing rust and in roughening the surfaces of these materials.
2. Description of the Background Art
A treatment called microetching which consists of chemically abrading copper surfaces is performed in the manufacture of printed-wiring boards for promoting adhesion of etching resists and solder resists and for improving the soldering performances when electronic components are fixed to the wiring boards. The microetching consists of chemically abrading the surfaces of copper using an aqueous solution comprising sulfuric acid and hydrogen peroxide or an aqueous solution comprising a persulfate, as major components.
The treatment using an etching agent comprising sulfuric acid and hydrogen peroxide or a persulfate, as major components, however, may cause corrosion of the wiring circuit and, in the worst case, may break the circuit, if the components in the etching agent remain in the substrate due to insufficient washing. These conventional etching agents produce mists during the treatment operation, which may pollute the working environment.
Therefore, there has been a desire for the development of a composition for the treatment of surfaces of copper and copper alloys, which does not cause corrosion of the circuit, does not involve a risk of the circuit breakage, and does not accompany the production of mists and noxious gases, thereby improving the circumstances where the printed-wiring boards are manufactured.
As a result of extensive studies, the present inventors have found that a combination a cupric complex of azole compound, specific organic acid, and specific complexing compounds can provide a surface treating agent which satisfies these requirements.